I heard a comic book podcast the other day play a song by a band called Icarus from a 1971 album Marvel Comics tried to produce, but due to many factors the project was shelved. And the host, while talking about the project, added that McCartney's Magneto & Titanium Man was written FOR this failed project.

First I've EVER heard this story, and read a couple of books centered around Paul's 1970s days.

So is this guy talking out his rear suggesting that McCartney sat on the song for around 4 or so years while other acts, like Icarus faded into music obscurity because of a failed Marvel album project?

I dont know about the failed Marvel album story, but the song was indeed written about Marvel villains Magneto (X-Men) and Titanium Man (Iron Man). Paul was a huge comic book fan, but again, if it was for a failed Marvel project, thats news to me. News I figured I would have heard before (being a comic geek myself), but maybe not.